Parallel H-shaped phenylenevinylenes: Quasi-coplanar molecules for highly luminescent blue OLEDs

For highly luminescent solid-state applications, the twisted or spiro-configured conjugated molecules are mostly considered as the proper choices because the coplanar ones usually have intensively intermolecular π–π interactions, which lead to fluorescence quenching and red-shift. In this study, the two prepared parallel H-shaped phenylenevinylenes with coplanar configuration show the special case. Due to their characteristics of multi-branches, these coplanar multi-branched molecules prefer to form stable amorphous morphology in thin films were verified by the XRDs and AFM. The amorphous thin films show very weak intermolecular actions, with intrinsic differences on both steady and transient optical properties from the crystalline states. The non-doped electroluminescent devices based on them show highly luminescent blue emissions. Both their luminance (20490 cd m−2) and efficiency (2.8 cd A−1/2.6 lm W−1) are comparable with the performances of the cross dimeric OPVs which have similar constructing blocks to the H-shaped molecules and with the same EL device configurations.